Formation probability of metastable molecular hydrogen anions H _mD _n ⁻ (m, n = 0–3 and m + n = 2, 3) in sputtering

Author(s)

Hubert Gnaser, Robin Golser

Abstract

The formation of molecular hydrogen anions (H-2(-), D-2(-), HD-, H-3(-), HD2-, and D-3(-)) was investigated. These anion species were produced by sputtering of TiD2 and HfH2 targets with Cs+ ions and were identified by secondary-ion mass spectrometry (SIMS), yielding the corresponding abundance distributions. The intensity ratios of both the diatomic (HD-/D-2(-)) and triatomic (HD2-/D-3(-)) molecular ions are (distinctly) lower than what would be expected from the respective statistical isotopic pattern. This observation indicates that the different lifetimes of these metastable anions are decisive for their formation probability in sputtering and their survival in the mass spectrometer. In addition to molecular ions, the isotopic fractionation of the atomic hydrogen ions, D-/H-, was determined. A strong depletion of the heavier D isotope in the sputtered ion flux by (47.0 +/- 3.1)% was found. This pronounced isotope fractionation could be due to a velocity-dependence of the ionization probability, amplified by the large mass difference of the hydrogen isotopes.

Organisation(s)

Isotope Physics

External organisation(s)

Technische Universität Kaiserslautern, Institut für Oberflächen- und Schichtanalytik GmbH, Kaiserslautern

Journal

International Journal of Mass Spectrometry

Volume

410

Pages

52-56

No. of pages

5

ISSN

1387-3806

DOI

https://doi.org/10.1016/j.ijms.2016.11.004

Publication date

11-2016

Peer reviewed

Yes

Austrian Fields of Science 2012

103014 Nuclear physics

Keywords

ASJC Scopus subject areas

Condensed Matter Physics, Instrumentation, Spectroscopy, Physical and Theoretical Chemistry

Portal url

https://ucrisportal.univie.ac.at/en/publications/d308abb1-dab6-4c07-8386-a83a2749b49e